The present invention relates to a method of lining the internal surface of a pipe, particularly to a method of lining the internal surface of an existing underground gas pipe, water pipe, etc. for the purpose of internal surface repair or rehabilitation thereof.
There have been suggested various methods of lining the internal surface of an existing pipe with a resin so as to carry out pipeline internal surface repair or rehabilitation thereof. For instance, Japanese Patent Gazette 61-24067 discloses a method where a predetermined amount of a liquid resin is introduced into an existing pipe to be treated, and is forced to move through the pipe, by means of a hight speed air flow, so that a desired resin lining layer is formed on the internal surface of the existing pipe.
FIG. 1 illustrates the above-mentioned prior art method. In FIG. 1, reference numeral 1 represents an existing underground pipe to be treated in the resin lining treatment, which is branching from a main pipe 2 and extending to a user's house.
In fact, the pipe 1 is used as a service pipe including a meter riser 3 which extends out of ground surface. The meter riser 3 is provided at one end thereof with a meter (not shown) which shall be removed therefrom so as to form a first open end for the resin lining operation. On the other hand, a pit A is formed by digging at a position where the service pipe 1 is branching from the main pipe 2, so that the branching position is exposed and the service pipe 1 is separated from the main pipe 2 by being separated from a service tee 4. In this way, a second open end is formed on the service pipe 1 for the resin lining operation.
In lining operation, an air blower 5 and a resin mixing/supplying apparatus 6 are connected to the first open end of the service pipe 1, whilst an extra resin receiving tank 8 is connected through a hose 7 to the second open end thereof.
By operating the air blower 5, an air flow having a high speed is generated to cause a mixed liquid resin (supplied from the resin mixing/supplying apparatus 6) to flow into the meter riser 3. Then, by means of the same air flow, the resin is forced to flow into and through the service pipe 1 toward the second open end thereof, so that a resin lining layer c is formed on the internal surface of the pipe 1. A small amount of an extra resin is caused to flow out of the pipe 1 so as to be received into the receiving tank 8 via the hose 7.
However, in the above-mentioned conventional method, the resin lining layer c formed on the internal surface of the surface pipe 1, has at least the following two defects as shown in FIGS. 4 and 5.
As illustrated in FIG. 4, before the resin lining layer c is solidified on the internal surface of the pipe 1, the resin on the top will flow down to the bottom of the pipe, resulting in a problem that the upper half of the resin lining layer c has a relatively thin thickness d, whereas the lower half of the resin lining layer c has a relatively thick thickness e.
As illustrated in FIG. 5, since a waving phenomenon g is easy to occur on the resin surface before the resin solidifies, the resin lining layer c finally formed on the inner wait of the pipe 1 presents an uneven surface, resulting in a lining layer having an ununiform thickness.
Since many experiments indicate that it is necessary to use a low viscosity resin which has a thixothropy property so that the resin may be exactly transported through a pipe along the entire length thereof, the above two problems as shown in FIGS. 4 and 5 have been proved to be difficult to overcome.